Measurement of background gamma radiation in the northern Marshall Islands

Gamma radiation levels on Bikini Island, part of the UNESCO-listed Bikini Atoll Nuclear Test Site, significantly exceed the agreed safety threshold for human habitation set by the U.S. and Republic of the Marshall Islands (RMI) governments (100 mrem/year or 1 mSv/year). Measurements on six northern Marshall Islands revealed mean radiation levels ranging from 7.6 mrem/year on Enewetak to 184 mrem/year on Bikini, with Rongelap showing elevated but sub-threshold levels (19.8 mrem/year). The study, conducted using gamma radiation detectors and interpolated mapping, highlights hot spots and compares findings to control sites like Majuro and New York City's Central Park. While external radiation on most islands is below the threshold, internal exposure via food ingestion remains a critical consideration for assessing resettlement safety.

Bordner, A. S., Crosswell, D. A., Katz, A. O., Shah, J. T., Zhang, C. R., Nikolic-Hughes, I., Hughes, E. W., & Ruderman, M. A. (2016). Measurement of background gamma radiation in the northern Marshall Islands. Proceedings of the National Academy of Sciences, 113(25), 6833–6838. https://doi.org/10.1073/pnas.1605535113